Commit b601c3bc authored by Ben Gardon's avatar Ben Gardon Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Factor out tdp_iter_return_to_root 



In tdp_mmu_iter_cond_resched there is a call to tdp_iter_start which
causes the iterator to continue its walk over the paging structure from
the root. This is needed after a yield as paging structure could have
been freed in the interim.

The tdp_iter_start call is not very clear and something of a hack. It
requires exposing tdp_iter fields not used elsewhere in tdp_mmu.c and
the effect is not obvious from the function name. Factor a more aptly
named function out of tdp_iter_start and call it from
tdp_mmu_iter_cond_resched and tdp_iter_start.

No functional change intended.

Signed-off-by: default avatarBen Gardon <bgardon@google.com>
Message-Id: <20210315233803.2706477-4-bgardon@google.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 14f6fec2

arch/x86/kvm/mmu/tdp_iter.c

+17 −7
Original line number Diff line number Diff line
@@ -20,6 +20,21 @@ static gfn_t round_gfn_for_level(gfn_t gfn, int level) 
	return gfn & -KVM_PAGES_PER_HPAGE(level);

}



/*

 * Return the TDP iterator to the root PT and allow it to continue its

 * traversal over the paging structure from there.

 */

void tdp_iter_restart(struct tdp_iter *iter)

{

	iter->yielded_gfn = iter->next_last_level_gfn;

	iter->level = iter->root_level;



	iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);

	tdp_iter_refresh_sptep(iter);



	iter->valid = true;

}



/*

 * Sets a TDP iterator to walk a pre-order traversal of the paging structure

 * rooted at root_pt, starting with the walk to translate next_last_level_gfn.
@@ -31,16 +46,11 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level, 
	WARN_ON(root_level > PT64_ROOT_MAX_LEVEL);



	iter->next_last_level_gfn = next_last_level_gfn;

	iter->yielded_gfn = iter->next_last_level_gfn;

	iter->root_level = root_level;

	iter->min_level = min_level;

	iter->level = root_level;

	iter->pt_path[iter->level - 1] = (tdp_ptep_t)root_pt;

	iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root_pt;



	iter->gfn = round_gfn_for_level(iter->next_last_level_gfn, iter->level);

	tdp_iter_refresh_sptep(iter);



	iter->valid = true;

	tdp_iter_restart(iter);

}



/*

arch/x86/kvm/mmu/tdp_iter.h

+1 −0
Original line number Diff line number Diff line
@@ -63,5 +63,6 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level, 
		    int min_level, gfn_t next_last_level_gfn);

void tdp_iter_next(struct tdp_iter *iter);

tdp_ptep_t tdp_iter_root_pt(struct tdp_iter *iter);

void tdp_iter_restart(struct tdp_iter *iter);



#endif /* __KVM_X86_MMU_TDP_ITER_H */

arch/x86/kvm/mmu/tdp_mmu.c

+1 −3
Original line number Diff line number Diff line
@@ -664,9 +664,7 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm, 


		WARN_ON(iter->gfn > iter->next_last_level_gfn);



		tdp_iter_start(iter, iter->pt_path[iter->root_level - 1],

			       iter->root_level, iter->min_level,

			       iter->next_last_level_gfn);

		tdp_iter_restart(iter);



		return true;

	}